Investigation of high-level waste glass melting using X-ray computed tomography

A method has been developed to quantitatively assess the melting behavior of simulated nuclear waste glasses in a 5-cm-diameter stainless steel beaker heated from the bottom. The method applies X-ray scanning and computed tomography to build three-dimensional volumetric data of a heat-treated sample and performs an adaptive segmentation analysis of the volumetric data to identify morphologically distinct regions in the sample matrix and quantify the amount of material in each region based on computed tomography density. The method was applied to two different series of simulated high-level waste glass melter feeds, and the results showed that it provides detailed images of samples at various stages of melting, including distribution of gas bubbles of varying sizes within the sample matrix, as well as a quantitative measure of how fast various waste/frit feeds melted relative to each other. The results show that the melting rate is influenced by the rate of calcine gas evolution, melt viscosity, and the presence of modifier ions in the feed.     

国外玻璃窑用耐火材料的新进展

本文介绍了国外玻璃窑用耐火材料、保温材料的新进展情况     

Conversion kinetics of container glass batch melting

Understanding the batch-to-glass conversion process is fundamental to optimizing the performance of glass-melting furnaces and ensuring that furnace modeling can correctly predict the observed outcome when batch materials or furnace conditions change. To investigate the kinetics of silica dissolution, gas evolution, and primary foam formation and collapse, we performed X-ray diffraction, thermal gravimetry, feed expansion tests, and evolved gas analysis of batch samples heated at several constant heating rates. We found that gas evolving reactions, foaming, and silica dissolution depend on the thermal history of the batch in a similar manner: the kinetic parameters of each process were linear functions of the square root of the heating rate. This kinetic similarity reflects the stronger-than-expected interdependence of these processes. On the basis of our results, we suggest that changes in furnace operating conditions, such as firing or boosting, influence the melting rate less than what one would expect without consideration of batch conversion kinetics.     

In-situ X-ray and visual observation of foam morphology and behavior at the batch-melt interface during melting of simulated waste glass

To attain a basic understanding of the primary foam structure and behavior, which affects the heat and mass transfer and the efficiency of the glass melting process, we investigated the primary foam layer under the glass batch floating on molten glass. The primary foam affects mass transfer during batch melting, in turn affecting the melting process. The recently performed direct in-situ three-dimensional X-ray computed tomography of the batch melting in a laboratory-scale melter vessel allowed us to visualize the features of the reacting batch layer and the foam that develops at its bottom, though with an insufficient resolution of images. In this study, we obtained better temporal and spatial resolution using the two-dimensional X-ray radiography and visual observation of the structure and behavior of transient primary foam as it formed and decayed. As soon as the batch was charged onto the melt surface, foam bubbles began to evolve, grow, and coalesce, forming a primary foam layer, 5–10 mm thick, within tens of seconds. This foam layer was sustained by ongoing gas evolving reactions counterbalanced by bubble coalescence into cavities that moved sideways and escaped to the atmosphere. Eventually, the entire remaining batch turned into foam that gradually decayed at the melt surface. The decay rate agreed with literature observations of surface foam produced by secondary foaming.     

玻璃熔窑用国产熔铸耐火材料的配套应用

论述了玻璃熔窑用国产熔铸耐火材料在配套方面应具备的基本条件和配套能力发展概况。推荐了玻璃熔窑重要部位的熔铸耐火材料品种、规格的配套方案,指出了配套中的问题,为进一步提高配套水平提出了改进意见。     

Effect of melting atmospheres on the optical property of radiation-hard fluorophosphate glass

High-energy radiation in space and nuclear irradiation environment induces colour centres in optical glass, causing solarisation, and a serious condition can render optical systems and optical loads unusable. To develop space radiation-resistant optical glass, CeO₂-stabilised radiation-hard fluorophosphate glass was prepared under three different atmospheres (nitrogen, oxygen, and ambient air). The glass-melting atmospheres' effects on the glass's transmission, defect formation, and structural changes before and after exposure to gamma radiation were investigated by a comprehensive study on their transmittance, absorption, and electron paramagnetic resonance spectra. Introducing a small amount of CeO₂ (～0.34 wt%) into the fluorophosphate base glass converted NBO and BO into ABO in the glass network, red-shifted the UV absorption edge, and decreased the optical density increment by almost half after radiation. As the total dose of gamma radiation increased, the transmittance of the irradiated glass at a wavelength of 385 nm significantly increased due to absorption of POHC2 defects. After exposure to 250 k of rad gamma irradiation, the corresponding optical density increment per centimeter thickness at 385 nm of the radiation-hard fluorophosphate glass that melted in the nitrogen, oxygen, and air atmospheres decreased from 1.839 to 1.388 and 1.215. As it melted in air, the NBO ratio of the fluorophosphate glass reached the lowest level and the Ce⁴⁺ ratio in the glass was 92.49%, which helped suppress the generation of POHC, Fe³⁺, PO₄-EC, and PO₃-EC defects during the gamma irradiation process, improving the glass's radiation resistance.     

玻璃窑用优质硅砖的相变及损毁机理

分析了残砖各段带的化学成分变化及相组成变化 ,指出硅砖的损毁机理是相变和蚀损。高纯致密的优质硅砖可以提高玻璃窑的使用效率和使用寿命     

Preparation and scintillation properties of Ce3+/Tb3+-co-doped oxyfluoride glass for high-resolution X-ray imaging

Scintillator glasses have the potential for X-ray imaging owing to their low production cost, controllable shape and size, and uniform ion-doping concentration. In this study, Tb³⁺-doped and Ce³⁺/Tb³⁺-co-doped oxyfluoride scintillator (C4T9) glass samples were fabricated by high-temperature melting and quenching. In addition, the luminescence properties of the glass samples and the discrepancy in the energy transfer mechanism between Ce³⁺ and Tb³⁺ under ultraviolet (UV) light and X-ray excitation were investigated. The C4T9 glass sample showed excellent integral scintillation efficiency of 84.1% for commercial Bi₄Ge₃O₁₂ (BGO) crystals. The spatial resolution of the C4T9 glass sample was higher than that of the commercial BGO crystal with 42.29 mGy s⁻¹ X-ray irradiation, reaching 16 lp·mm⁻¹. C4T9 glass is expected to become a key material in medical imaging, safety inspection, industrial inspection, and other fields.     

浮法玻璃熔窑卡脖处水包压入深度对玻璃液流动影响的数值研究

采用数值模拟方法,分析了置于浮法玻璃熔窑卡脖中间处的水包压入深度对窑池和卡脖内玻璃液流动状态的影响,并计算了不同水包压入深度时的卡脖出、人口处生产流及回流量。结果表明：随着水包压入深度适当增加,有利于减少玻璃液回流,降低热耗。卡脖处压入水包,玻璃液流动状态在卡脖内发生变化,水包前后的环流强度增加,有助于玻璃液均化和澄清,提高玻璃的成形质量。     

Modeling batch melting: Roles of heat transfer and reaction kinetics

Development of mathematical models of heat and mass transfer in glass-melting furnaces began in the 1970s and progressed rapidly with advances in sophisticated experimental/numerical techniques and increasing computational power. Today, practically all newly built or rebuilt furnaces are optimized with these models to meet stringent quality requirements, reduce the unit costs of manufacturing, or control emissions. One remaining hurdle is to model the batch-to-glass conversion accurately enough to reliably assess the glass production rate. This article summarizes two key aspects of the batch-conversion modeling—the heat transfer and the kinetics of conversion—and reviews the current state-of-the-art approaches to simulating them. We critically examine the advantages of the commonly used heat transfer approach, but also explain that its predictive capabilities are significantly restricted by the dependence of batch thermal properties on the time-temperature history. We argue that kinetic approaches to the batch-conversion modeling would offer a significant improvement when coupled with the heat transfer approach. Finally, we summarize key areas requiring further research on the way toward a realistic model of the batch blanket.     

玻璃纤维池窑用致密Cr_2O_3制品的开发

以高纯工业Cr2 O3为原料 ,研究了工艺因素和添加剂对Cr2 O3制品性能的影响。结果表明 :复合添加剂对Cr2 O3制品性能和烧结性的作用优于单一组分添加剂。该复合添加剂的作用机理是 :活化Cr2 O3晶格 ,强化其晶粒间的结合程度 ,在Cr2O3晶粒周围形成一层高熔点的环状新生相 ,这种新生相既可阻止Cr2 O3晶粒长大 ,驱动Cr2 O3晶粒紧密结合 ,又可防止Cr2 O3进一步与O2 亲合 ,在较低温度下就可显著促进Cr2 O3的烧结     

Electrolyte effects on recirculating dense bubbly flow: An experimental study using X-ray imaging

In this work, the effect of an electrolyte (up to 2 M of NaCl dissolved in water) on a homogeneous dense bubbly flow, in an airlift bubble column, is studied using nonintrusive techniques. X-ray and high-speed imaging are used to investigate the bubble size distribution, the local and the global gas-fraction profiles. The major effect of the electrolyte is the bubble size distribution at the fine-pore sparger, which is a consequence of the bubble coalescence inhibition promoted by the electrolyte. The bubble plume widening, the increase in overall gas fraction, and the onset of bubble recirculation in the column can all be explained by the bubble size reduction at the fine-pore spargers. As a result of the bubble size reduction, the overall role of the electrolyte is in a reduction of the driving force for the liquid recirculation. Furthermore, an accumulation of the small bubbles causes a layer of foam at the free surface, which is dynamic in nature and induces additional bubble recirculation.     

熔融态黄磷炉渣的综合利用现状

电炉法制备黄磷产生的工业固体废物——黄磷炉渣,属于化工废渣。黄磷熔融炉渣,根据冷却方式的不同,可分为水淬渣和自然冷却黄磷炉渣,我国主要是水淬渣。本文综述了黄磷炉渣用于微晶玻璃、水泥工业、硅钙肥、路基材料、陶瓷材料、白炭黑、玻璃材料、砖、稀土元素等领域,同时对熔融态黄磷炉渣出炉时温度高达1200～1300 ℃的热量充分利用进行了探讨,直接用来制造建筑装饰用微晶玻璃,达到保护环境和黄磷行业清洁生产的目的。     

BaZrO3 refractory crucibles for vacuum induction melting of industrial Zr-based bulk metallic glass master alloys with Y addition

The absence of appropriate melting method and expensive cost of high-purity Zr raw material limit the commercial application of Zr-based bulk metallic glass. In the present study, using high oxygen industrial grade sponge Zr as raw material and the metal Y as additive, the low-cost and high-purity master alloys were successively prepared using a VIM method with a BaZrO₃ refractory crucible. The results indicate that the BaZrO₃ refractory exhibited good erosion resistance to the alloy melt, the Y additive formed the Y₂O₃ barrier layer on the surface of crucible, which prevented the melt permeation into the crucible, then effectively reduced the thickness of the erosion layer. In addition, the metal Y deoxidizer could remove the oxygen of melts, finally the low oxygen Zr-based master alloy (about 0.02 wt%) was prepared. These results may provide a promising preparing technique prototype of low-cost Zr-based bulk metallic glass.     

碱性耐火材料在白银炼铜炉上的使用

简述了炼钢炉的原理及特点，镁铝、镁络耐火材料的性能及其在炼铜炉上的使用。初探了炼钢炉渣线部位用普通镁铝砖、半再结合镁铬砖的损毁机理，结果表明：半再结合镁络砖的抗侵蚀性明显优于普通镁铝砖。     

玻璃窑炉池壁的绑砖操作

通过对玻璃窑炉池壁成功实施绑砖,消除了威胁窑炉运行安全的一大隐患,延长了窑炉的使用寿命,创造了良好的节能效果。